summaryrefslogtreecommitdiffstats
blob: 703484c21446672708ed785e2a5cdd80e39a10d5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
/* libs/diskconfig/diskconfig.c
 *
 * Copyright 2008, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "config_mbr"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include <cutils/log.h>

#include <diskconfig/diskconfig.h>


/* start and len are in LBA units */
static void
cfg_pentry(struct pc_partition *pentry, uint8_t status, uint8_t type,
           uint32_t start, uint32_t len)
{
    if (len > 0) {
        /* seems that somes BIOSens can get wedged on boot while verifying
         * the mbr if these are 0 */
        memset(&pentry->start, 0xff, sizeof(struct chs));
        memset(&pentry->end, 0xff, sizeof(struct chs));
    } else {
        /* zero out the c/h/s entries.. they are not used */
        memset(&pentry->start, 0, sizeof(struct chs));
        memset(&pentry->end, 0, sizeof(struct chs));
    }

    pentry->status = status;
    pentry->type = type;
    pentry->start_lba = start;
    pentry->len_lba = len;

    ALOGI("Configuring pentry. status=0x%x type=0x%x start_lba=%u len_lba=%u",
         pentry->status, pentry->type, pentry->start_lba, pentry->len_lba);
}


static inline uint32_t
kb_to_lba(uint32_t len_kb, uint32_t sect_size)
{
    uint64_t lba;

    lba = (uint64_t)len_kb * 1024;
    /* bump it up to the next LBA boundary just in case  */
    lba = (lba + (uint64_t)sect_size - 1) & ~((uint64_t)sect_size - 1);
    lba /= (uint64_t)sect_size;
    if (lba >= 0xffffffffULL)
        ALOGE("Error converting kb -> lba. 32bit overflow, expect weirdness");
    return (uint32_t)(lba & 0xffffffffULL);
}


static struct write_list *
mk_pri_pentry(struct disk_info *dinfo, struct part_info *pinfo, int pnum,
              uint32_t *lba)
{
    struct write_list *item;
    struct pc_partition *pentry;

    if (pnum >= PC_NUM_BOOT_RECORD_PARTS) {
        ALOGE("Maximum number of primary partition exceeded.");
        return NULL;
    }

    if (!(item = alloc_wl(sizeof(struct pc_partition)))) {
        ALOGE("Unable to allocate memory for partition entry.");
        return NULL;
    }

    {
        /* DO NOT DEREFERENCE */
        struct pc_boot_record *mbr = (void *)PC_MBR_DISK_OFFSET; 
        /* grab the offset in mbr where to write this partition entry. */
        item->offset = (loff_t)((uint32_t)((uint8_t *)(&mbr->ptable[pnum])));
    }

    pentry = (struct pc_partition *) &item->data;

    /* need a standard primary partition entry */
    if (pinfo) {
        /* need this to be 64 bit in case len_kb is large */
        uint64_t len_lba; 

        if (pinfo->len_kb != (uint32_t)-1) {
            /* bump it up to the next LBA boundary just in case */
            len_lba = ((uint64_t)pinfo->len_kb * 1024);
            len_lba += ((uint64_t)dinfo->sect_size - 1);
            len_lba &= ~((uint64_t)dinfo->sect_size - 1);
            len_lba /= (uint64_t)dinfo->sect_size;
        } else {
            /* make it fill the rest of disk */
            len_lba = dinfo->num_lba - *lba;
        }

        cfg_pentry(pentry, ((pinfo->flags & PART_ACTIVE_FLAG) ?
                            PC_PART_ACTIVE : PC_PART_NORMAL),
                   pinfo->type, *lba, (uint32_t)len_lba);

        pinfo->start_lba = *lba;
        *lba += (uint32_t)len_lba;
    } else {
        /* this should be made an extended partition, and should take
         * up the rest of the disk as a primary partition */
        cfg_pentry(pentry, PC_PART_NORMAL, PC_PART_TYPE_EXTENDED,
                   *lba, dinfo->num_lba - *lba);

        /* note that we do not update the *lba because we now have to
         * create a chain of extended partition tables, and first one is at
         * *lba */
    }

    return item;
}


/* This function configures an extended boot record at the beginning of an
 * extended partition. This creates a logical partition and a pointer to
 * the next EBR.
 *
 * ext_lba == The start of the toplevel extended partition (pointed to by the
 * entry in the MBR).
 */
static struct write_list *
mk_ext_pentry(struct disk_info *dinfo, struct part_info *pinfo, uint32_t *lba,
              uint32_t ext_lba, struct part_info *pnext)
{
    struct write_list *item;
    struct pc_boot_record *ebr;
    uint32_t len; /* in lba units */

    if (!(item = alloc_wl(sizeof(struct pc_boot_record)))) {
        ALOGE("Unable to allocate memory for EBR.");
        return NULL;
    }

    /* we are going to write the ebr at the current LBA, and then bump the
     * lba counter since that is where the logical data partition will start */
    item->offset = (*lba) * dinfo->sect_size;
    (*lba)++;

    ebr = (struct pc_boot_record *) &item->data;
    memset(ebr, 0, sizeof(struct pc_boot_record));
    ebr->mbr_sig = PC_BIOS_BOOT_SIG;

    if (pinfo->len_kb != (uint32_t)-1)
        len = kb_to_lba(pinfo->len_kb, dinfo->sect_size);
    else {
        if (pnext) {
            ALOGE("Only the last partition can be specified to fill the disk "
                 "(name = '%s')", pinfo->name);
            goto fail;
        }
        len = dinfo->num_lba - *lba;
        /* update the pinfo structure to reflect the new size, for
         * bookkeeping */
        pinfo->len_kb =
            (uint32_t)(((uint64_t)len * (uint64_t)dinfo->sect_size) /
                       ((uint64_t)1024));
    }

    cfg_pentry(&ebr->ptable[PC_EBR_LOGICAL_PART], PC_PART_NORMAL,
               pinfo->type, 1, len);

    pinfo->start_lba = *lba;
    *lba += len;

    /* If this is not the last partition, we have to create a link to the
     * next extended partition.
     *
     * Otherwise, there's nothing to do since the "pointer entry" is
     * already zero-filled.
     */
    if (pnext) {
        /* The start lba for next partition is an offset from the beginning
         * of the top-level extended partition */
        uint32_t next_start_lba = *lba - ext_lba;
        uint32_t next_len_lba;
        if (pnext->len_kb != (uint32_t)-1)
            next_len_lba = 1 + kb_to_lba(pnext->len_kb, dinfo->sect_size);
        else
            next_len_lba = dinfo->num_lba - *lba;
        cfg_pentry(&ebr->ptable[PC_EBR_NEXT_PTR_PART], PC_PART_NORMAL,
                   PC_PART_TYPE_EXTENDED, next_start_lba, next_len_lba);
    }

    return item;

fail:
    free_wl(item);
    return NULL;
}


struct write_list *
config_mbr(struct disk_info *dinfo)
{
    struct part_info *pinfo;
    uint32_t cur_lba = dinfo->skip_lba;
    uint32_t ext_lba = 0;
    struct write_list *wr_list = NULL;
    struct write_list *temp_wr = NULL;
    int cnt = 0;
    int extended = 0;

    if (!dinfo->part_lst)
        return NULL;

    for (cnt = 0; cnt < dinfo->num_parts; ++cnt) {
        pinfo = &dinfo->part_lst[cnt];

        /* Should we create an extedned partition? */
        if (cnt == (PC_NUM_BOOT_RECORD_PARTS - 1)) {
            if (cnt + 1 < dinfo->num_parts) {
                extended = 1;
                ext_lba = cur_lba;
                if ((temp_wr = mk_pri_pentry(dinfo, NULL, cnt, &cur_lba)))
                    wlist_add(&wr_list, temp_wr);
                else {
                    ALOGE("Cannot create primary extended partition.");
                    goto fail;
                }
            }
        }

        /* if extended, need 1 lba for ebr */
        if ((cur_lba + extended) >= dinfo->num_lba)
            goto nospace;
        else if (pinfo->len_kb != (uint32_t)-1) {
            uint32_t sz_lba = (pinfo->len_kb / dinfo->sect_size) * 1024;
            if ((cur_lba + sz_lba + extended) > dinfo->num_lba)
                goto nospace;
        }

        if (!extended)
            temp_wr = mk_pri_pentry(dinfo, pinfo, cnt, &cur_lba);
        else {
            struct part_info *pnext;
            pnext = cnt + 1 < dinfo->num_parts ? &dinfo->part_lst[cnt+1] : NULL;
            temp_wr = mk_ext_pentry(dinfo, pinfo, &cur_lba, ext_lba, pnext);
        }

        if (temp_wr)
            wlist_add(&wr_list, temp_wr);
        else {
            ALOGE("Cannot create partition %d (%s).", cnt, pinfo->name);
            goto fail;
        }
    }

    /* fill in the rest of the MBR with empty parts (if needed). */
    for (; cnt < PC_NUM_BOOT_RECORD_PARTS; ++cnt) {
        struct part_info blank;
        cur_lba = 0;
        memset(&blank, 0, sizeof(struct part_info));
        if (!(temp_wr = mk_pri_pentry(dinfo, &blank, cnt, &cur_lba))) {
            ALOGE("Cannot create blank partition %d.", cnt);
            goto fail;
        }
        wlist_add(&wr_list, temp_wr);
    }

    return wr_list;

nospace:
    ALOGE("Not enough space to add parttion '%s'.", pinfo->name);

fail:
    wlist_free(wr_list);
    return NULL;
}


/* Returns the device path of the partition referred to by 'name'
 * Must be freed by the caller.
 */
char *
find_mbr_part(struct disk_info *dinfo, const char *name)
{
    struct part_info *plist = dinfo->part_lst;
    int num = 0;
    char *dev_name = NULL;
    int has_extended = (dinfo->num_parts > PC_NUM_BOOT_RECORD_PARTS);

    for(num = 1; num <= dinfo->num_parts; ++num) {
        if (!strcmp(plist[num-1].name, name))
            break;
    }

    if (num > dinfo->num_parts)
        return NULL;

    if (has_extended && (num >= PC_NUM_BOOT_RECORD_PARTS))
        num++;

    if (!(dev_name = malloc(MAX_NAME_LEN))) {
        ALOGE("Cannot allocate memory.");
        return NULL;
    }

    num = snprintf(dev_name, MAX_NAME_LEN, "%s%d", dinfo->device, num);
    if (num >= MAX_NAME_LEN) {
        ALOGE("Device name is too long?!");
        free(dev_name);
        return NULL;
    }

    return dev_name;
}